Among the major achievements of the program in the last three years we include: (1) cloning and sequencing of HTLV-II; (2) identification of the chi transcript from HTLV-I and -II, and identification and characterization of the chi-encoded protein; (3) determination of the intracellular biology of the chi protein, and demonstration that the chi gene is required for efficient transcription; (4) purification of erythroid-potentiating activity and its cDNA and genomic cloning and expresson in eukaryotic cells; (5) purification of GM-CSF and demonstration of its identity with NIF-T; (6) cDNA and genomic cloning of GM-CSF; (7) production of recombinant GM-CSF; (8) identification and purification of a T-lymphocyte-derived factor that stimulates the growth and differentiation of glial cells referred to as glial growth-promoting factor (GGPF); (9) identification and characterization of an abnormal c-abl oncogene product in chronic myelogenous leukemia (P210 c-abl) with activated tyrosine kinase activity and its correlation with the existence of the Philadelphia chromosome; (10) demonstration that the 22 and 55 kilodalton E1B proteins are required for adenovirus-induced cellular transformation; (11) demonstration of the cellular oncogenes expressed during embryonic and fetal development and classification of oncogene expression in fresh human malignant tissue; and (12) demonstration of specific effects of gamma interferon on HLA-D expression and vitamin D metabolism of normal and neoplastic myeloid cells. (V)